Group texture packs under one picker section and add a Download from OrcaCloud shortcut

The texture picker lists every plugin pack as an indented, collapsible child of one
"Resource Texture" section, which now always renders so the new button is reachable even
before any pack is installed. A pack whose name carries a " by ..." suffix shows that part
on a smaller, dimmed second line, keeping the name line short.

The button switches to the Home tab and opens the OrcaCloud pane on the plugin hub filtered
to resource textures. A native open now also drives the homepage shell (nav highlight and the
cloud-mode layout), and the requested page is remembered so a sign-in re-seed keeps it.

Also fixes the PluginsDialog fuzzy-search script path, which pointed at a directory the file
is not in.

src/slic3r/GUI/GUI_App.cpp

@@ -5467,12 +5467,7 @@ std::string GUI_App::handle_web_request(std::string cmd)
                 this->request_open_project({});
             }
             else if (command_str.compare("homepage_open_cloud") == 0) {
-                // Deferred: set_cloud_mode() may create a second native webview, which must
-                // not run inside this webview's script-message callback.
-                CallAfter([this]() {
-                    if (WebViewPanel* home = WebViewPanel::if_built())
-                        home->set_cloud_mode(true, cloud_webview_handoff());
-                });
+                this->open_orca_cloud();
             }
             else if (command_str.compare("homepage_close_cloud") == 0) {
                 CallAfter([]() {
@@ -5621,6 +5616,22 @@ std::string GUI_App::handle_web_request(std::string cmd)
     return "";
 }
 
+void GUI_App::open_orca_cloud(const std::string& next)
+{
+    // Remembered so a login while the pane is open re-seeds the same page rather than the default.
+    m_cloud_open_path = next;
+    // Deferred: set_cloud_mode() may create the second native webview, so this must not run inside
+    // the caller's frame (a webview script-message callback or an ImGui frame).
+    CallAfter([this]() {
+        if (mainframe != nullptr)
+            mainframe->select_tab(TAB_ID_HOME);
+        // The Home page is built lazily, so the tab switch may not have created it yet: ensure() builds
+        // it if needed, matching what showing the tab does, rather than dropping the open request.
+        if (WebViewPanel* home = WebViewPanel::ensure())
+            home->set_cloud_mode(true, cloud_webview_handoff(m_cloud_open_path));
+    });
+}
+
 void GUI_App::handle_script_message(std::string msg, const std::string& provider)
 {
     try {
@@ -5898,7 +5909,7 @@ void GUI_App::on_update_machine_list(wxCommandEvent &evt)
      }*/
 }
 
-wxString GUI_App::cloud_webview_handoff()
+wxString GUI_App::cloud_webview_handoff(const std::string& next)
 {
     // The cloud pane loads the Start URL, not a token: the page checks the webview's own session
     // and asks for a handoff itself (guide §4). Signed out, user_id is omitted and the page will
@@ -5906,7 +5917,7 @@ wxString GUI_App::cloud_webview_handoff()
     auto orca = get_orca_cloud_agent(m_agent);
     if (!orca)
         return {};
-    return from_u8(orca->build_web_session_start_url());
+    return from_u8(orca->build_web_session_start_url(next));
 }
 
 void GUI_App::request_cloud_web_session(const std::string& state)
@@ -6049,7 +6060,7 @@ void GUI_App::on_user_login_handle(wxCommandEvent &evt)
     m_cloud_handoff_state.clear();
     if (WebViewPanel* home = WebViewPanel::if_built())
         if (home->cloud_mode_active())
-            home->set_cloud_mode(true, cloud_webview_handoff());
+            home->set_cloud_mode(true, cloud_webview_handoff(m_cloud_open_path));
 }